1. Field of the Invention
The present invention relates to a construction method of a steel composite girder bridge, and more particularly, to a construction method of a steel composite girder bridge, in which a cast-in-place deck has non-composite cross sections when applying pre-stress, and after the pre-stress has been applied, the non-composite cross sections act as composite sections by filling each position of shearing connectors with non-shrinkage mortar.
2. Description of the Related Arts
Generally, a bridge is a kind of overhead structure for crossing rivers, lakes and marshes, straits, bays, canals, lowlands, traffic routes or any other structures. As shown FIG. 1, the bridge is divided into an upper structure 10 and a lower structure 20.
The upper structure 10 is placed on abutments 22 or piers 24 and generally comprises girders 12 or slabs 14.
The type of the bridge is determined by the shape of a main member, generally, which receives the most power. In case that the main member is a girder 12, the bridge is referred to as a girder bridge. The slabs 14 are decks on which vehicles can run and in which concrete is cast. The lower structure 20 comprises the abutments 22 or the piers 24 which transfer a load applied from the upper structure 10 to the ground safely.
The abutments 22 are end supporting points of the bridge and the piers 24 are intermediate supporting points except for the end supporting points. According to the state of the ground under the piers 24, the type of foundation such as a direct foundation, a pile foundation, a caisson foundation is determined, and a base slab 26 is placed in each lower part of the piers 24.
On the other hand, there are some methods of casting concrete into the slabs 14 which are decks. One method is a cast-in-place method in which concrete is cast in a construction site, and another method is a pre-cast method in which concrete previously made in a factory is used.
Because the cast-in-place is performed in a construction site, tensile stress is occurred in each negative moment section of supporting points on the upper part of the bridge, so that the cross section of the decks is not valid. If the pre-stress is applied to the decks, even though the tensile stress for the negative moment is occurred, the cross section of the decks is valid in compressive stress state by the pre-stress.
In the conventional methods, when applying the pre-stress, a pre-cast deck is used, but economical efficiency is lowered. Alternatively, in case of applying the pre-stress to a cast-in-place deck, the pre-stress is applied in the state in which the deck is composed with the girder. Thus, there is a problem that the state of stress can be bad by compressive stress occurred in the girder.